Polydactyly

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (June 2008)

Polydactyly
Classification and external resources
Bilateral polydactyly with short fingers in an Ellis-van Creveld syndrome patient.
ICD-10	Q69.
ICD-9	755.0
OMIM	603598
DiseasesDB	24853
eMedicine	derm/692

Polydactyly or polydactylism (from Ancient Greek πολύς (polus) "many" + δάκτυλος (daktulos) "finger"), also known as hyperdactyly, is a congenital physical anomaly in humans having supernumerary fingers or toes. When each hand or foot has six digits, it is sometimes called sexdactyly, hexadactyly, or hexadactylism.

The extra digit is usually a small piece of soft tissue; occasionally it contains bone without joints; rarely it may be a complete, functioning digit. The extra digit is most common on the ulnar (little finger) side of the hand, less common on the radial (thumb) side, and very rarely within the middle three digits. These are respectively known as postaxial (little finger), preaxial (thumb), and central (ring, middle, index fingers) polydactyly. The extra digit is most commonly an abnormal fork in an existing digit, or it may rarely originate at the wrist as a normal digit does.^[1]

Polydactyly can occur by itself, or more commonly, as one feature of a syndrome of congenital anomalies. When it occurs by itself, it is associated with autosomal dominant mutations in single genes, i.e. it is not a multifactorial trait.^[2] But mutation in a variety of genes can give rise to polydactyly. Typically the mutated gene is involved in developmental patterning, and a syndrome of congenital anomalies results, of which polydactyly is one feature.

The condition has an incidence of 1 in every 500 live births.^[3] Postaxial hand polydactyly is a common isolated disorder in African black and African American children, and autosomal dominant transmission is suspected. Postaxial polydactyly is approximately 10 times more frequent in blacks than in whites and is more frequent in male children.^[4] In contrast, postaxial polydactyly seen in white children is usually syndromic and associated with an autosomal recessive transmission. One study by Finley et al. combined data from Jefferson County, Alabama, United States and Uppsala County, Sweden. This study showed incidence of all types of polydactyly to be 2.3 per 1000 in white males, 0.6 per 1000 in white females, 13.5 per 1000 in black males, and 11.1 per 1000 in black females.^[5]

Left foot with postaxial polydactyly of 5th ray

Right hand with mid-ray duplication

In various species

Cats normally have five digits on the front feet and four on the rear. Polydactyl cats have more, and this is a moderately common condition, especially in certain cat populations.

A number of mutations of the LMBR1 gene, in dogs, humans, and mice, can cause polydactyly.^[6] Dogs, like other canids, normally have four claws on their rear paws; a fifth is often called a dewclaw and is especially found in certain dog breeds,^[6] including the Norwegian Lundehund and Great Pyrenees.

Real human polydactyls

• Hrithik Roshan, a Bollywood actor born with a supernumerary thumb on his right hand.^[7]
• Antonio Alfonseca, a Major League Baseball pitcher.
• Hampton Hawes, jazz pianist, was born with six fingers on each hand (surgically removed shortly after birth)^[8]
• Little Tich, an English music hall comedian.
• Garfield Sobers, West Indian cricketer, had an extra finger on each hand which he removed himself during childhood "with the aid of catgut and a sharp knife".^[9]
• Gemma Arterton,^{[10] [11]} actress.
• Toyotomi Hideyoshi, Japanese daimyo who unified Japan in the Sengoku period.
• Sid Wilson, turntablist of Slipknot. He was born with an extra digit on his hands and feet. They were dead, however, and were removed shortly after birth.
• Blues guitarist Hound Dog Taylor[2]
• Roman era poet Volcatius Sedigitus.

Fictional, mythological and biblical human polydactyls

• Hannibal Lecter, the fictional psychiatrist and serial murderer, had a sixth finger on his left hand. Its removal is crucial to the plot of the novel Hannibal.
• Swartt and Veil Sixclaw, fictional anthropomorphic ferrets from Brian Jacques's book series, Redwall, were both polydactyls. It was stated in the novel that Veil inherited polydactylism from his father, Swartt.
• Count Rugen, one of the villains in the novel and movie The Princess Bride, had six fingers on his right hand, by which feature Inigo Montoya was able to identify him as the man who had killed his father. Also, this made finding a good sword difficult for the count.
• In Gattaca, the main characters attend a concert of a twelve fingered pianist.
• In the television series Monk, Adrian Monk's wife was murdered by a six-fingered man named Frank Nunn.
• Sophie Wender, in The Chrysalids, conceals that she has six toes on each foot, in a society where mutants are hunted down.
• Legend states that Anne Boleyn, second wife of Henry VIII, had this disorder, but an 1857 exhumation of her body disproved this.
• One of the sons of the biblical giant, Goliath, is said to have had six fingers on each hand and six toes on each foot:

  2 Samuel 21:20

  And there was yet a battle in Gath, where was a man of great stature, that had on every hand six fingers, and on every foot six toes, four and twenty in number; and he also was born to the giant. - KJV

  1 Chronicles 20:6

  And yet again there was war at Gath, where was a man of great stature, whose fingers and toes were four and twenty, six on each hand, and six on each foot and he also was the son of the giant. - KJV

• In the visual novel, Umineko no Naku Koro ni, Kinzo Ushiromiya (右代宮 金蔵), head of the Ushiromiya family, is known for having six toes on each foot. This was later used to identify his body, which was found burned in the incinerator in the underground boiler room.
• In numerous episodes of Zoey 101, it is stated that Quinn has six toes on her right foot.
• The twins in Slapstick, a novel by Kurt Vonnegut
• In the manga & anime series Shigurui, Iwamoto Kogan, head of the Kogan-Ryu sword school, has six fingers on his right hand.
• Cú Chulainn, a mythological hero in the Ulster Cycle of Celtic mythology is described in The Táin as being a Polydactyl; "Each foot had seven toes and each hand seven fingers"

See also

Polydactyl cat

• Dactyly (generic term for the arrangement of digits)
• Polycephaly (extra head(s))
• Polymelia (extra limb(s))
• Supernumerary body part
• Syndactyly (digits fused together)

Additional images

A photograph of a 27 year old male with unilateral polydactyly affecting the left thumb. The supernumerary digit had normal sensation but no joint and hence could not move independently.

Preaxial polydactyly.

Postaxial polydactyly.

Preaxial polydactyly.

References

http://www.pennmedicine.org/encyclopedia/em_displayArticle.aspx?gcid=003176&ptid=1 http://www.eatonhand.com/hw/hw024.htm

Wikimedia Commons has media related to: Polydactyly